feat: 添加基金邮件定时发送功能并优化邮件内容格式

- 新增宝塔面板定时任务脚本 cron_send_email.php
- 添加手动发送邮件按钮到管理界面
- 使用PHPMailer替代原始SMTP实现
- 优化邮件内容格式，按涨跌幅排序基金数据
- 增加邮件发送时间窗口判断逻辑
- 更新项目文档说明定时任务配置

data/visits.json

@@ -4324,5 +4324,26 @@
         "timestamp": 1765511264,
         "date": "2025-12-12 04:47:44",
         "referer": "http:\/\/localhost:8080\/2\/?ide_webview_request_time=1765511263860"
+    },
+    {
+        "ip": "Unknown",
+        "user_agent": "Unknown",
+        "timestamp": 1765521796,
+        "date": "2025-12-12 07:43:16",
+        "referer": "Direct"
+    },
+    {
+        "ip": "::1",
+        "user_agent": "Mozilla\/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit\/537.36 (KHTML, like Gecko) TraeCN\/1.104.3 Chrome\/138.0.7204.251 Electron\/37.6.1 Safari\/537.36",
+        "timestamp": 1765522828,
+        "date": "2025-12-12 08:00:28",
+        "referer": "http:\/\/localhost:8080\/2\/?ide_webview_request_time=1765522826051"
+    },
+    {
+        "ip": "::1",
+        "user_agent": "Mozilla\/5.0 (Windows NT; Windows NT 10.0; zh-CN) WindowsPowerShell\/5.1.26100.4768",
+        "timestamp": 1765523454,
+        "date": "2025-12-12 08:10:54",
+        "referer": "Direct"
     }
 ]